[syzbot] [bcachefs?] KASAN: global-out-of-bounds Read in rcu_pending_exit

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7b1d1d4cfac0 Merge remote-tracking branch 'iommu/arm/smmu'..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=116f6930580000
kernel config: https://syzkaller.appspot.com/x/.config?x=dfe1e340fbee3d16
dashboard link: https://syzkaller.appspot.com/bug?extid=e733ab672a1b6724c27f
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/354fe38e2935/disk-7b1d1d4c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f12e0b1ef3fd/vmlinux-7b1d1d4c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/291dbc519bb3/Image-7b1d1d4c.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e733ab...@syzkaller.appspotmail.com

------------[ cut here ]------------
==================================================================
BUG: KASAN: global-out-of-bounds in string_nocheck lib/vsprintf.c:646 [inline]
BUG: KASAN: global-out-of-bounds in string+0x1dc/0x264 lib/vsprintf.c:728
Read of size 1 at addr ffff80008bacf4cb by task syz-executor/6428

CPU: 1 UID: 0 PID: 6428 Comm: syz-executor Not tainted 6.12.0-syzkaller-g7b1d1d4cfac0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call trace:
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:484 (C)
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:377 [inline]
print_report+0x198/0x538 mm/kasan/report.c:488
kasan_report+0xd8/0x138 mm/kasan/report.c:601
__asan_report_load1_noabort+0x20/0x2c mm/kasan/report_generic.c:378
string_nocheck lib/vsprintf.c:646 [inline]
string+0x1dc/0x264 lib/vsprintf.c:728
vsnprintf+0xe9c/0x1a8c lib/vsprintf.c:2803
vprintk_store+0x38c/0xd80 kernel/printk/printk.c:2260
vprintk_emit+0x258/0x55c kernel/printk/printk.c:2383
vprintk_default+0xa0/0xe4 kernel/printk/printk.c:2422
vprintk+0x200/0x300 kernel/printk/printk_safe.c:68
__warn_printk+0x2b0/0x484 kernel/panic.c:797
look_up_lock_class+0xec/0x160 kernel/locking/lockdep.c:936
register_lock_class+0x8c/0x6b4 kernel/locking/lockdep.c:1290
__lock_acquire+0x18c/0x77c8 kernel/locking/lockdep.c:5077
lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5825
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
_raw_spin_lock_irq+0x58/0x70 kernel/locking/spinlock.c:170
spin_lock_irq include/linux/spinlock.h:376 [inline]
rcu_pending_has_pending_or_armed fs/bcachefs/rcu_pending.c:576 [inline]
rcu_pending_exit+0x124/0x660 fs/bcachefs/rcu_pending.c:594
bch2_fs_btree_key_cache_exit+0x7ec/0x8f4 fs/bcachefs/btree_key_cache.c:742
__bch2_fs_free fs/bcachefs/super.c:556 [inline]
bch2_fs_release+0x1fc/0x728 fs/bcachefs/super.c:611
kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x2a8/0x41c lib/kobject.c:737
bch2_fs_free+0x2c4/0x334 fs/bcachefs/super.c:673
bch2_kill_sb+0x48/0x58 fs/bcachefs/fs.c:2279
deactivate_locked_super+0xc4/0x12c fs/super.c:473
deactivate_super+0xe0/0x100 fs/super.c:506
cleanup_mnt+0x34c/0x3dc fs/namespace.c:1373
__cleanup_mnt+0x20/0x30 fs/namespace.c:1380
task_work_run+0x230/0x2e0 kernel/task_work.c:239
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
do_notify_resume+0x178/0x1f4 arch/arm64/kernel/entry-common.c:151
exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:169 [inline]
exit_to_user_mode arch/arm64/kernel/entry-common.c:178 [inline]
el0_svc+0xac/0x168 arch/arm64/kernel/entry-common.c:745
el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

The buggy address belongs to the variable:
.str+0xb/0x20

The buggy address belongs to the virtual mapping at
[ffff80008b5d0000, ffff80008f330000) created by:
declare_kernel_vmas+0x58/0xb8 arch/arm64/mm/mmu.c:771

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1a22cf
flags: 0x5ffc00000002000(reserved|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000002000 fffffdffc588b3c8 fffffdffc588b3c8 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff80008bacf380: 00 f9 f9 f9 00 06 f9 f9 00 00 00 00 f9 f9 f9 f9
ffff80008bacf400: 00 00 00 00 00 00 f9 f9 f9 f9 f9 f9 00 00 00 00
>ffff80008bacf480: 00 00 00 00 00 00 00 00 00 01 f9 f9 00 00 00 04
^
ffff80008bacf500: f9 f9 f9 f9 00 00 00 00 00 00 00 00 00 00 00 00
ffff80008bacf580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
Looking for class "" with key rcu_pending_init.__key, but found a different class "&p->lock" with the same key
WARNING: CPU: 1 PID: 6428 at kernel/locking/lockdep.c:939 look_up_lock_class+0xec/0x160 kernel/locking/lockdep.c:936
Modules linked in:
CPU: 1 UID: 0 PID: 6428 Comm: syz-executor Tainted: G B 6.12.0-syzkaller-g7b1d1d4cfac0 #0
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : look_up_lock_class+0xec/0x160 kernel/locking/lockdep.c:936
lr : look_up_lock_class+0xec/0x160 kernel/locking/lockdep.c:936
sp : ffff8000a42773e0
x29: ffff8000a42773e0 x28: dfff800000000000 x27: 0000000000000000
x26: ffff8000973468c0 x25: ffff800097346000 x24: 0000000000000001
x23: 0000000000000000 x22: 1ffff00011f040ba x21: ffff8000974ed7c0
x20: fffffdffbf7434b0 x19: ffff800092e7e3c0 x18: 0000000000000008
x17: 20646e756f662074 x16: ffff8000830d1d70 x15: 0000000000000001
x14: 1fffe000366cb0e2 x13: 0000000000000000 x12: 0000000000000000
x11: 0000000000000003 x10: 0000000000ff0100 x9 : 19ffed0552c97800
x8 : 19ffed0552c97800 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff8000a4276b18 x4 : ffff80008f90d220 x3 : ffff800080626d8c
x2 : 0000000000000001 x1 : 0000000100000001 x0 : 0000000000000000
Call trace:
look_up_lock_class+0xec/0x160 kernel/locking/lockdep.c:936 (P)
look_up_lock_class+0xec/0x160 kernel/locking/lockdep.c:936 (L)
register_lock_class+0x8c/0x6b4 kernel/locking/lockdep.c:1290
__lock_acquire+0x18c/0x77c8 kernel/locking/lockdep.c:5077
lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5825
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
_raw_spin_lock_irq+0x58/0x70 kernel/locking/spinlock.c:170
spin_lock_irq include/linux/spinlock.h:376 [inline]
rcu_pending_has_pending_or_armed fs/bcachefs/rcu_pending.c:576 [inline]
rcu_pending_exit+0x124/0x660 fs/bcachefs/rcu_pending.c:594
bch2_fs_btree_key_cache_exit+0x7ec/0x8f4 fs/bcachefs/btree_key_cache.c:742
__bch2_fs_free fs/bcachefs/super.c:556 [inline]
bch2_fs_release+0x1fc/0x728 fs/bcachefs/super.c:611
kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x2a8/0x41c lib/kobject.c:737
bch2_fs_free+0x2c4/0x334 fs/bcachefs/super.c:673
bch2_kill_sb+0x48/0x58 fs/bcachefs/fs.c:2279
deactivate_locked_super+0xc4/0x12c fs/super.c:473
deactivate_super+0xe0/0x100 fs/super.c:506
cleanup_mnt+0x34c/0x3dc fs/namespace.c:1373
__cleanup_mnt+0x20/0x30 fs/namespace.c:1380
task_work_run+0x230/0x2e0 kernel/task_work.c:239
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
do_notify_resume+0x178/0x1f4 arch/arm64/kernel/entry-common.c:151
exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:169 [inline]
exit_to_user_mode arch/arm64/kernel/entry-common.c:178 [inline]
el0_svc+0xac/0x168 arch/arm64/kernel/entry-common.c:745
el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
irq event stamp: 282192
hardirqs last enabled at (282191): [<ffff80008b5a7504>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
hardirqs last enabled at (282191): [<ffff80008b5a7504>] _raw_spin_unlock_irqrestore+0x38/0x98 kernel/locking/spinlock.c:194
hardirqs last disabled at (282192): [<ffff80008b5a73ac>] __raw_spin_lock_irq include/linux/spinlock_api_smp.h:117 [inline]
hardirqs last disabled at (282192): [<ffff80008b5a73ac>] _raw_spin_lock_irq+0x28/0x70 kernel/locking/spinlock.c:170
softirqs last enabled at (280764): [<ffff80008020396c>] softirq_handle_end kernel/softirq.c:400 [inline]
softirqs last enabled at (280764): [<ffff80008020396c>] handle_softirqs+0xa38/0xbf8 kernel/softirq.c:582
softirqs last disabled at (280725): [<ffff800080020db4>] __do_softirq+0x14/0x20 kernel/softirq.c:588
---[ end trace 0000000000000000 ]---


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: eabcdba3ad40 Merge tag 'for-6.13-rc3-tag' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=170e77e8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1234f097ee657d8b

dashboard link: https://syzkaller.appspot.com/bug?extid=e733ab672a1b6724c27f
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12834cf8580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7a4dff87674a/disk-eabcdba3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/266bc2b7ced3/vmlinux-eabcdba3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ee4bcd9be832/bzImage-eabcdba3.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/7bfbea1d3e96/mount_2.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e733ab...@syzkaller.appspotmail.com

------------[ cut here ]------------
==================================================================
BUG: KASAN: global-out-of-bounds in string_nocheck lib/vsprintf.c:646 [inline]

BUG: KASAN: global-out-of-bounds in string+0x218/0x2b0 lib/vsprintf.c:728
Read of size 1 at addr ffffffff8c53984a by task syz.0.174/7554

CPU: 1 UID: 0 PID: 7554 Comm: syz.0.174 Not tainted 6.13.0-rc3-syzkaller-00073-geabcdba3ad40 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0x169/0x550 mm/kasan/report.c:489
kasan_report+0x143/0x180 mm/kasan/report.c:602
string_nocheck lib/vsprintf.c:646 [inline]
string+0x218/0x2b0 lib/vsprintf.c:728
vsnprintf+0x1101/0x1da0 lib/vsprintf.c:2848
vprintk_store+0x485/0x1240 kernel/printk/printk.c:2279
vprintk_emit+0x271/0xa10 kernel/printk/printk.c:2408
__warn_printk+0x263/0x360 kernel/panic.c:797
look_up_lock_class+0xdb/0x170 kernel/locking/lockdep.c:936
register_lock_class+0x102/0x980 kernel/locking/lockdep.c:1290
__lock_acquire+0xf3/0x2100 kernel/locking/lockdep.c:5101
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
_raw_spin_lock_irq+0xd3/0x120 kernel/locking/spinlock.c:170

spin_lock_irq include/linux/spinlock.h:376 [inline]
rcu_pending_has_pending_or_armed fs/bcachefs/rcu_pending.c:576 [inline]

rcu_pending_exit+0x13f/0x7a0 fs/bcachefs/rcu_pending.c:594
bch2_fs_btree_key_cache_exit+0x97f/0xab0 fs/bcachefs/btree_key_cache.c:741
__bch2_fs_free fs/bcachefs/super.c:556 [inline]
bch2_fs_release+0x206/0x7d0 fs/bcachefs/super.c:611

kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]

kobject_put+0x22f/0x480 lib/kobject.c:737
bch2_fs_alloc fs/bcachefs/super.c:960 [inline]
bch2_fs_open+0x1ebe/0x2f80 fs/bcachefs/super.c:2065
bch2_fs_get_tree+0x738/0x1710 fs/bcachefs/fs.c:2157
vfs_get_tree+0x90/0x2b0 fs/super.c:1814
do_new_mount+0x2be/0xb40 fs/namespace.c:3507
do_mount fs/namespace.c:3847 [inline]
__do_sys_mount fs/namespace.c:4057 [inline]
__se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4034
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb98f7874ca
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb99051be68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fb99051bef0 RCX: 00007fb98f7874ca
RDX: 00000000200000c0 RSI: 0000000020000000 RDI: 00007fb99051beb0
RBP: 00000000200000c0 R08: 00007fb99051bef0 R09: 0000000000800000
R10: 0000000000800000 R11: 0000000000000246 R12: 0000000020000000
R13: 00007fb99051beb0 R14: 0000000000005938 R15: 0000000020005b00
</TASK>

The buggy address belongs to the variable:

.str+0xa/0x20

The buggy address belongs to the physical page:

page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xc539
flags: 0xfff00000002000(reserved|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000002000 ffffea0000314e48 ffffea0000314e48 0000000000000000

raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

page_owner info is not present (never set?)

Memory state around the buggy address:

ffffffff8c539700: 02 f9 f9 f9 00 00 06 f9 f9 f9 f9 f9 00 00 03 f9
ffffffff8c539780: f9 f9 f9 f9 00 00 00 00 f9 f9 f9 f9 00 00 00 00
>ffffffff8c539800: 00 00 00 00 00 00 00 00 00 01 f9 f9 00 00 00 04
^
ffffffff8c539880: f9 f9 f9 f9 00 00 00 00 00 00 00 00 00 00 00 00
ffffffff8c539900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

[syzbot]

syzbot has bisected this issue to:

commit d97de0d017cde0d442c3d144b4f969f43064cc0f
Author: Kent Overstreet <kent.ov...@linux.dev>
Date: Tue Aug 13 01:31:25 2024 +0000

bcachefs: Make bkey_fsck_err() a wrapper around fsck_err()

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=13432ef8580000
start commit: 8155b4ef3466 Add linux-next specific files for 20241220
git tree: linux-next
final oops: https://syzkaller.appspot.com/x/report.txt?x=10c32ef8580000
console output: https://syzkaller.appspot.com/x/log.txt?x=17432ef8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9c90bb7161a56c88
dashboard link: https://syzkaller.appspot.com/bug?extid=e733ab672a1b6724c27f
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17f5b418580000

Reported-by: syzbot+e733ab...@syzkaller.appspotmail.com
Fixes: d97de0d017cd ("bcachefs: Make bkey_fsck_err() a wrapper around fsck_err()")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 87a132e73910 Merge tag 'mm-hotfixes-stable-2025-02-19-17-4..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=175775b0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b7bde34acd8f53b1

dashboard link: https://syzkaller.appspot.com/bug?extid=e733ab672a1b6724c27f
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16d8aba4580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11e1dae4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4a88f50cb21d/disk-87a132e7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d970e0210e8a/vmlinux-87a132e7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9b6329058ef7/bzImage-87a132e7.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/f06af6381842/mount_0.gz

The issue was bisected to:

commit d97de0d017cde0d442c3d144b4f969f43064cc0f
Author: Kent Overstreet <kent.ov...@linux.dev>
Date: Tue Aug 13 01:31:25 2024 +0000

bcachefs: Make bkey_fsck_err() a wrapper around fsck_err()

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=13432ef8580000

final oops: https://syzkaller.appspot.com/x/report.txt?x=10c32ef8580000
console output: https://syzkaller.appspot.com/x/log.txt?x=17432ef8580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e733ab...@syzkaller.appspotmail.com

Fixes: d97de0d017cd ("bcachefs: Make bkey_fsck_err() a wrapper around fsck_err()")

------------[ cut here ]------------
==================================================================

BUG: KASAN: global-out-of-bounds in string_nocheck lib/vsprintf.c:632 [inline]
BUG: KASAN: global-out-of-bounds in string+0x229/0x2b0 lib/vsprintf.c:714
Read of size 1 at addr ffffffff8c74c10a by task syz-executor504/5826

CPU: 1 UID: 0 PID: 5826 Comm: syz-executor504 Not tainted 6.14.0-rc3-syzkaller-00079-g87a132e73910 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024

Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120

print_address_description mm/kasan/report.c:408 [inline]
print_report+0x16e/0x5b0 mm/kasan/report.c:521
kasan_report+0x143/0x180 mm/kasan/report.c:634
string_nocheck lib/vsprintf.c:632 [inline]
string+0x229/0x2b0 lib/vsprintf.c:714
vsnprintf+0x8b4/0x1220 lib/vsprintf.c:2843
vprintk_store+0x482/0x1240 kernel/printk/printk.c:2279

vprintk_emit+0x271/0xa10 kernel/printk/printk.c:2408
__warn_printk+0x263/0x360 kernel/panic.c:797

look_up_lock_class+0xdb/0x170 kernel/locking/lockdep.c:938
register_lock_class+0x102/0x980 kernel/locking/lockdep.c:1292
__lock_acquire+0xf3/0x2100 kernel/locking/lockdep.c:5103
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
_raw_spin_lock_irq+0xd3/0x120 kernel/locking/spinlock.c:170
spin_lock_irq include/linux/spinlock.h:376 [inline]
rcu_pending_has_pending_or_armed fs/bcachefs/rcu_pending.c:592 [inline]
rcu_pending_exit+0x13f/0x7a0 fs/bcachefs/rcu_pending.c:610
bch2_fs_btree_key_cache_exit+0x8d1/0x9f0 fs/bcachefs/btree_key_cache.c:778
__bch2_fs_free fs/bcachefs/super.c:569 [inline]
bch2_fs_release+0x206/0x7b0 fs/bcachefs/super.c:624

kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]

kobject_put+0x231/0x480 lib/kobject.c:737
deactivate_locked_super+0xc6/0x130 fs/super.c:473
cleanup_mnt+0x41f/0x4b0 fs/namespace.c:1413
task_work_run+0x251/0x310 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x13f/0x340 kernel/entry/common.c:218
do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7e807c2577
Code: 07 00 48 83 c4 08 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffeee02cd28 EFLAGS: 00000206 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f7e807c2577
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffeee02cde0
RBP: 00007ffeee02cde0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000206 R12: 00007ffeee02de50
R13: 000055557adeb6c0 R14: 431bde82d7b634db R15: 00007ffeee02de70
</TASK>

The buggy address belongs to the variable:

.str+0xa/0x20

The buggy address belongs to the physical page:

page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xc74c

flags: 0xfff00000002000(reserved|node=0|zone=1|lastcpupid=0x7ff)

raw: 00fff00000002000 ffffea000031d308 ffffea000031d308 0000000000000000

raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

page_owner info is not present (never set?)

Memory state around the buggy address:

ffffffff8c74c000: 00 05 f9 f9 02 f9 f9 f9 06 f9 f9 f9 00 00 00 00
ffffffff8c74c080: f9 f9 f9 f9 00 00 00 00 00 00 00 00 00 00 00 00
>ffffffff8c74c100: 00 01 f9 f9 00 00 00 04 f9 f9 f9 f9 00 00 00 00
^
ffffffff8c74c180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffffff8c74c200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

[syzbot]

syzbot suspects this issue was fixed by commit:

commit f2c61db29f277b9c80de92102fc532cc247495cd
Author: Linus Torvalds <torv...@linux-foundation.org>
Date: Mon Sep 29 20:43:52 2025 +0000

Remove bcachefs core code

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15440258580000
start commit: 87a132e73910 Merge tag 'mm-hotfixes-stable-2025-02-19-17-4..
git tree: upstream

kernel config: https://syzkaller.appspot.com/x/.config?x=b7bde34acd8f53b1
dashboard link: https://syzkaller.appspot.com/bug?extid=e733ab672a1b6724c27f

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16d8aba4580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11e1dae4580000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: Remove bcachefs core code

[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.